Illumination unit and liquid crystal display apparatus comprising same

ABSTRACT

A liquid crystal display device comprising a lighting unit of the present invention is aimed to inhibit a liquid crystal panel  111  from breaking by a pressure from a display surface side of a liquid crystal cell  111 , and to inhibit entry of dust having influence on display. Such lighting unit is structured in a way that a fluorescent discharge tube  2  is disposed close to an incident side end face E 1  of a light guiding plate  1 , and the end face E 1  of the light guiding plate  1  and the fluorescent discharge tube  2 , an end face E 2  and a bottom surface of the light guiding plate  1  are covered with a reflecting sheet  3 . A light correction sheet  4  is disposed on an emanating surface of the light guiding plate  1 , and these components are stored in an electrically conductive casing  9 . A spacing H of a space between the light correction sheet  4  and the light guiding plate  1  is set to not larger than one pixel dimension of the liquid crystal cell  111 . The casing  9  has an opening portion J on a light emanating surface side, and a display rear surface side polarizer  13   a  of a liquid crystal panel  11  is disposed in direct contact with a front surface of the light correction sheet  4  within the opening portion J.

TECHNICAL FIELD

The present invention relates both to a lighting unit and to a liquidcrystal display device using the same.

BACKGROUND ART

Recently, a liquid crystal display device has been widely used as adisplay device of an information device such as a notebook-type personalcomputer, a word processor and the like, or as a display device of avideo device such as a portable television, a video movie, a carnavigation system and the like, by taking advantage of a characteristicin which the liquid crystal device is light and thin, and consumes smallelectricity. Such liquid crystal display device typically has astructure in which a liquid crystal panel is illuminated from behind bya built-in lighting unit for obtaining a bright display screen. Theliquid crystal panel comprises at least a liquid crystal cell comprisinga pair of transparent substrates such as glass substrates, with a liquidcrystal layer interposed therebetween, and a pair of polarizers providedso as to retain the liquid crystal cell between them. As a structure ofsuch a lighting unit, there is an edge light type in which a lightguiding plate is disposed on a rear surface of the liquid crystal panel,and a linear light source such as a fluorescent discharge tube isdisposed on an end face of the light guiding plate, for example. Theedge light type excels in achieving a thin liquid crystal display deviceand a light emitting surface thereof with a uniform luminance. So, thisis commonly adopted as a backlight type of the liquid crystal displaydevice used in the notebook-type personal computer or the like. In theliquid crystal display device used in the portable television, the carnavigation system and the like, the edge light type using two or morefluorescent discharge tubes, or the edge light type using an L-shaped ora U-shaped fluorescent discharge tube is commonly adopted, for obtaininga thin and luminous liquid crystal display.

In the edge light type in which the fluorescent discharge tube isdisposed on the end face of the light guiding plate, it is important toreduce the size of the liquid crystal display device by storingcomponents such as the light guiding plate, the fluorescent dischargetube, a lead wire or the like within a casing, for improving acharacteristic of the liquid crystal display device such as portabilityand compactness.

Today, the liquid crystal display device is used in all householdappliances in addition to the above-described uses. For example, theliquid crystal display device is commonly used in products used insevere surroundings, such as outside, owing to a portability thereof.Therefore, it becomes more important to consider about a warranty for afunction of such products.

FIG. 4 is a cross-sectional view schematically showing a structure ofthe lighting unit of a conventional edge light type, comprising thefluorescent discharge tube, and of the liquid crystal display devicecomprising the lighting unit. FIGS. 5( a) and 5(b) are viewsschematically showing a structure of the lighting unit in FIG. 4,wherein FIG. 5( a) is a plan view and FIG. 5( b) is a side view. Asshown in FIGS. 4, 5(a), and 5(b), the lighting unit comprises aflat-plate shaped transparent light guiding plate 1, configured totransmit light, an L-shaped fluorescent discharge tube 2 provided closeto two of four sides of the light guiding plate 1, a reflecting sheet 3for inhibiting light emitted from the fluorescent discharge tube 2 fromemanating out of the light guiding plate 1, a casing 9 for holding thesecomponents, and a light correction sheet 4 provided on a light emanatingsurface side of the light guiding plate 1,

The reflecting sheet 3 is bent so as to enclose the fluorescentdischarge tube 2 disposed on an end face E1 of the light guiding plate1, and an end portion of the reflecting sheet 3 is bonded to the lightemanating surface of the light guiding plate 1 by a double face adhesivetape 10. Thereby, the light emitted from the fluorescent discharge tube2 is guided into the light guiding plate 1 from the end face E1 of thelight guiding plate 1 without leakage. The reflecting sheet 3 is alsodisposed on a rear surface (an opposite surface of the light emanatingsurface) of the light guiding plate 1, for reflecting the lightemanating from the rear surface of the light guiding plate 1, and forreturning the light into the light guiding plate 1. Furthermore, thereflecting sheet 3 is bent along an end face E2 of the light guidingplate 1 so as to cover the end face E2, on which the fluorescentdischarge tube 2 is not provided. Thus structured, the light emanatingfrom the end face E2 of the light guiding plate 1 is reflected by thereflecting sheet 3 and is returned into the light guiding plate 1. Bythus returning the light emanating from the light guiding plate 1 intothe same by the reflecting sheet 3, the light (i.e., an illuminationlight) emanating from the light emanating surface of the light guidingplate 1 is increased, thereby enabling the light to be used moreefficiently.

As the reflecting sheet 3, a white resinous film having a highreflectivity is used, for example. The reflecting sheet 3 may bestructured by using separate sheets disposed so as to correspond to aperiphery of the fluorescent discharge tube 2, the rear surface of thelight guiding plate 1, and the end face E2 of the light guiding plate 1.In this case, an integral-type sheet that continuously covers theseportions is used. By using the integral-type reflecting sheet 3, a thinlighting unit, a cost reduction thereof, and a reduction of the numberof assembly processes thereof are realized.

The light correction sheet 4 is disposed on the light emanating surfaceof the light guiding plate 1, for obtaining a uniform and highlyluminous illumination light. The light correction sheet 4 comprises aplurality of optical sheets of various specifications as necessary.Herein, two light correction sheets 4 are provided, as shown in FIG. 4.

The light guiding plate 1 and the fluorescent discharge tube 2, whichare covered with the reflecting sheet 3, and the light correction sheet4, are held by the casing 9. The lighting unit is formed by thesecomponents thus stored in the casing 9. The casing 9 is frame-shaped soas to have an opening portion J and comprises an edge portion 9 a and aside portion 9 b. By forming the opening portion J, a display region Aof a liquid crystal panel 11 to be described below is located within theopening portion J, and the edge portion 9 a of the casing 9 encloses thedisplay region A, in a plan view. A through-hole G which communicateswith outside is provided on the side portion 9 b of the casing 9, for aweight saving and an installation by a user. Furthermore, the lightcorrection sheet 4 and the light guiding plate 1 are disposed so as toform a space (hereinafter, referred to as a clearance F) between themand an inner wall of the casing 9. By forming the clearance F, itbecomes possible to absorb a dimension difference by the clearance F,when the light correction sheet 4, the light guiding plate 1, and thecasing 9 expand with different expansion rates due to a temperaturevariation, thereby resulting in the dimension difference. Therefore, itbecomes possible to inhibit occurrence of distortion or the like due tothe dimension difference.

Furthermore, on the edge portion 9 a of the casing 9 of the lightingunit, a liquid crystal panel 11 comprising a display rear surface sidepolarizer 13 a, a display front surface side polarizer 13 b, and aliquid crystal cell 111 comprising at least a pair of transparentsubstrates which retain a liquid crystal layer between them is provided.The liquid crystal panel 11 is fixed to the edge portion 9 a of thecasing 9 by a double face adhesive tape 14. And, a front cover 12 isprovided so as to cover these components. A liquid crystal displaydevice is obtained by thus disposing the liquid crystal panel 11 on thelight emanating surface side of the lighting unit.

Since the display rear surface side polarizer 13 a is disposed on thecasing 9, as described above, a space 15 is formed between a bottomsurface of the polarizer 13 a and the light emanating surface of thelighting unit (an upper surface of the light correction sheet 4, to bemore precise). Therefore, there is a problem that, the liquid crystalcell 111 deflects as much as the space 15 when a user accidentallypushes the display surface of the liquid crystal display device, so thatthe liquid crystal cell 111 comprising the glass substrates or the likeis broken.

On the other hand, as described above, since the casing 9 has thethrough-hole G, dust might enter the casing (i. e., the lighting unit)from outside through the through-hole G. The entering dust might alsoenter the display region such as a vicinity of the light correctionsheet 4 and the light guiding plate 1 through the clearance F. In thelighting unit and the liquid crystal display device thus structured, anouter size thereof is limited for obtaining a compact device, and thusit is often impossible to provide a component for inhibiting entry ofthe dust. Therefore, the dust entering from outside as described above,or being generated inside when assembling the device passes through theclearance F and enters a space between the light guiding plate 1 and thelight correction sheet 4, or between the light correction sheet 4 or thelike and the liquid crystal panel 11. The dust entering the spaceinterrupts an output light when displaying an image, thereby causingnon-uniform luminance to occur, or conceals pixels, thereby causingdisplay defects. Also, there is a possibility that a component of thedisplay region side such as the light correction sheet 4 is damaged by afriction between components and the dust. Once the dust enters a spacebetween the liquid crystal panel 11 and the lighting unit, it is verydifficult to clear the dust away without disassembling the device.Therefore, it is very important to inhibit the dust from entering thedisplay region.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a lighting unitcapable of inhibiting damage to a liquid crystal cell by a pressure froma display surface side of a panel, and a liquid crystal display devicecomprising the same. A second object thereof is to provide a liquidcrystal display device comprising a lighting unit capable of inhibitingdust from entering a display region.

In order to achieve the above objects, according to the presentinvention, there is provided a lighting unit comprising a light source,a light guiding component for guiding light emitted from the lightsource and emanating the light from a light emanating surface to anobject to be illuminated, a reflecting component covering at least abottom surface of the light guiding component, a light correctioncomponent disposed on the light emanating surface of the light guidingcomponent, and a casing for holding the light source, the light guidingcomponent covered with the reflecting component, and the lightcorrection component, wherein the casing has an opening portion in aregion corresponding to a light emanating region of the light correctioncomponent, and the object to be illuminated is disposed in directcontact with an upper surface of the light correction component withinthe opening portion.

In such a configuration, since the object to be illuminated by thelighting unit is attached to the lighting unit in direct contact with afront surface of the light correction component within the openingportion formed in the casing, little space is formed between the lightcorrection component and the object to be illuminated. So, when apressure is applied from a principal surface side of the object to beilluminated, a large part of the front surface of the light correctioncomponent contacts the object so as to support this, so that it becomespossible to inhibit occurrence of deformation such as deflection or thelike in the object. Therefore, it is possible to inhibit damage to theobject to be illuminated.

The liquid crystal display device according to the present inventioncomprises the lighting unit according to the above-described presentinvention, and a liquid crystal panel as the object to be illuminateddisposed on the light emanating surface side of the lighting unit, theliquid crystal panel having the liquid crystal cell comprising a pair oftransparent substrates with a liquid crystal layer interposedtherebetween, wherein the liquid crystal panel is disposed in directcontact with the front surface of the light correction component withinthe opening portion of the casing of the lighting unit.

In such a configuration, since the liquid crystal panel as the object tobe illuminated is disposed in direct contact with the light correctioncomponent within the opening portion of the casing of the lighting unit,little space is formed between a rear surface of the liquid crystalpanel (i. e., an opposite surface of the display surface) and the lightcorrection component. So, when a pressure is applied from the displaysurface side to the device, the liquid crystal cell composing the liquidcrystal panel is supported by the light correction component, and henceby a large part of an upper surface of the light guiding component.Therefore, it becomes possible to inhibit occurrence of deformation suchas deflection or the like in the liquid crystal cell. As a result, it ispossible to inhibit damage to the liquid crystal cell, such as break.

The liquid crystal panel may comprise a pair of polarizers with theliquid crystal cell interposed therebetween, and a lighting unit sidepolarizer of the pair of polarizers may have an outer diameter smallerthan that of the opening portion of the casing, and may directly contactthe front surface of the light correction component within the openingportion.

In such a configuration, since the outer diameter of the opening portionof the casing is larger than that of the polarizer on the lighting unitside, it becomes possible to dispose the polarizer within the openingportion and to allow the polarizer to directly contact the lightcorrection component.

The casing may have a frame-shaped edge portion protruding toward theopening portion so as to enclose the opening portion, and the liquidcrystal cell may be disposed on an upper surface of the edge portionthereof.

In such a configuration, the edge portion of the casing can hold thelight guiding component, the light correction component and the likefrom above (a light emanating side). Also, positioning of the liquidcrystal cell becomes easier, and the liquid crystal cell can be fixed tothe edge portion of the casing by using an adhesive tape or the like.

A thickness of the edge portion of the casing may be substantially equalto that of the polarizer on the lighting unit side.

In such a configuration, since the edge portion of the casing and thepolarizer have substantially the same thickness, an upper surface of theedge portion and an upper surface of the polarizer are substantiallycoplanar with each other. With the liquid crystal cell disposed on theseflat upper surfaces of the edge portion and of the polarizer, sincethese flat surfaces contact the liquid crystal cell so as tosubstantially uniformly support the cell, it is possible to inhibitdamage to the liquid crystal cell.

The casing may be made of an electrically conductive material.

In such a configuration, by the casing, it becomes possible to inhibit anoise from entering an electronic component of the liquid crystaldisplay device by influence of an electromagnetic wave or the likegenerated from the light source.

In the lighting unit, a spacing of a space formed between the lightguiding component and the light correction component is preferably notlarger than a dimension of each of pixels composing the liquid crystalpanel. For example, this is preferably 0.4 mm or smaller.

In such a configuration, a structure in which only dust not larger thanone pixel dimension might enter the space between the light guidingcomponent and the light correction component is realized. Since suchsmall dust does not have large influence on a display image and aluminance, good display can be obtained.

The casing may have a through-hole to allow an outside of the casing andan inside of the casing to communicate with each other.

In such a configuration, the through-hole makes it possible to achieve athin device and to facilitate an installation thereof by a user. Also,in this configuration provided with the through-hole, the dust entersinside of the lighting unit from outside through the through-hole, butsince the structure in which only the dust not larger than one pixeldimension might enter the display region is realized as described above,it is possible to realize the above-described effect while inhibitinginfluence of the entered dust on the display image and the luminance.

The light guiding component may be a light guiding plate, the lightsource may be disposed along a first end face of the light guidingplate, the reflecting component may be a reflecting sheet, a bottomsurface of the light guiding plate, the first end face of the lightguiding plate and the light source, and a second end face of the lightguiding plate on which the light source is not disposed may be coveredwith the reflecting sheet, the light correction component may be a lightcorrection sheet, and the casing may be frame-shaped and may support atleast the bottom surface of the light guiding plate, the second end faceof the light guiding plate, and the first end face of the light guidingplate and the light source, each of which is covered with the reflectingsheet.

In such a configuration, it is possible to realize the liquid crystaldisplay device comprising the lighting unit of an edge light type, andto obtain a thin and light device.

The object, as well as other objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription of the preferred embodiments taken with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a structure of alighting unit and a liquid crystal display device comprising the sameaccording to an embodiment of the present invention;

FIG. 2 is a perspective plan view schematically showing the structure ofthe lighting unit in FIG. 1;

FIG. 3 is a cross-sectional view schematically showing a structure of alighting unit and a liquid crystal display device comprising the sameaccording to another embodiment of the present invention;

FIG. 4 is a cross-sectional view schematically showing a structure of alighting unit and a liquid crystal display device comprising the sameaccording to a prior art; and

FIGS. 5( a) and 5(b) are views schematically showing the structure ofthe lighting unit in FIG. 4, wherein 5(a) is a perspective plan view and5(b) is a side view.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a structure of alighting unit and a liquid crystal display device comprising the sameaccording to a first embodiment of the present invention. FIG. 2 is aperspective plan view of the lighting unit in FIG. 1, in which a lightcorrection sheet is omitted.

As shown in FIGS. 1 and 2, the lighting unit comprises a flat-plateshaped transparent light guiding plate 1 configured to transmit light,an L-shaped fluorescent discharge tube 2 provided along an end face E1of the light guiding plate 1, as a light source, a reflecting sheet 3which covers the end face E1 of the light guiding plate 1 and thefluorescent discharge tube 2, an end face E2 of the light guiding plate1 on which the fluorescent discharge tube 2 is not provided, and abottom surface of the light guiding plate 1, a light correction sheet 4provided on a light emanating surface side of the light guiding plate 1,and a casing 9 for holding these components.

The light guiding plate 1 is made of a material having opticalcharacteristics, such as transmissivity and a refractive index or thelike required for transmitting light, for example, a material such asacrylic, which is optimal in the optical characteristic. A dot patternor a groove pattern (not shown) for scattering light, which varies itsshape according to a distance from the fluorescent discharge tube 2, isformed on a bottom surface of the light guiding plate 1.

The reflecting sheet 3 is made of a white and highly reflectivematerial, and is comprised of an integral-type sheet that continuouslycovers the fluorescent discharge tube 2 and the end face E1 of the lightguiding plate, the end face E2 of the light guiding plate 1, and thebottom surface of the light guiding plate 1. The reflecting sheet 3 isdisposed so as to cover the bottom surface of the light guiding plate 1,and is bent in U-shape along a periphery of the fluorescent dischargetube 2 disposed on the end face E1 of the light guiding plate 1, and anend portion of the reflecting sheet 3 is bonded to a light emanatingsurface of the light guiding plate 1 by an adhesive tape 10 such as adouble face adhesive tape. The reflecting sheet 3 is also bent along theend face E2 of the light guiding plate 1. By the reflecting sheet 3 thuscovering the end faces E1 and E2 and the bottom surface of the lightguiding plate 1, it becomes possible to guide a light emitted from thefluorescent discharge tube 2 into the light guiding plate 1 through theend face E1 thereof, and to return the light emanating outside from theend face E2 and the bottom surface of the light guiding plate 1 into thelight guiding plate 1 by reflecting it. This increases the light (thatis to say, an illumination light) emanating from the light emanatingsurface of the light guiding plate 1, thereby enabling the light to beused more efficiently. Although the integral-type reflecting sheet 3 isused herein, the reflecting sheet 3 may be structured by using separatesheets respectively covering the end face E1 of the light guiding plate1 and the fluorescent discharge tube 2, the bottom surface of the lightguiding plate 1, and the end face E2 of the light guiding plate 1. Byusing the integral-type reflecting sheet 3 as in this embodiment, a thinlighting unit, a cost reduction thereof, and a reduction of the numberof assembly processes thereof are realized.

The light correction sheet 4 is provided on the light emanating surfaceside of the light guiding plate 1. Herein, a space 15 is formed betweenthe light emanating surface of the light guiding plate 1 and the lowersurface of the light correction sheet 4, and a spacing H of the space 15is not larger than one pixel dimension of a crystal liquid cell used,for example, 0.4 mm or smaller. As the light correction sheet 4, aplurality of sheets of various specifications having the opticalcharacteristic may be provided as necessary, and herein, two lightcorrection sheets 4 are provided. For example, the light correctionsheet 4 is constituted by a diffusion sheet, a prismatic sheet and thelike. By thus providing the light correction sheet 4, it becomespossible to make the light emanating from the lighting unit uniform andhighly luminous.

After assembling a lighting element 20 by thus disposing the fluorescentdischarge tube 2, the light guiding plate 1, the reflecting sheet 3, andthe light correction sheet 4, the lighting element 20 is stored in thecasing 9. Thus, the lighting unit is formed. The casing 9 isframe-shaped, comprising an edge portion 9 a and a side portion 9 b, andis configured to support the lighting element 20 in a vertical directionby the edge portion 9 a and in a horizontal direction by the sideportion 9 b.

The casing 9 disposed on the light emanating surface side of thelighting element 20 has an opening portion J. As described below, theopening portion J is sized so as not to interfere with a display rearsurface side polarizer 13 a of a liquid crystal panel 11 disposed on thelighting unit, that is, sized to be larger than the polarizer 13 a andto be able to contain it. Furthermore, the opening portion J is sized tobe smaller than a crystal liquid cell 111 comprising at least a pair oftransparent substrates with a liquid crystal layer interposedtherebetween, and to allow the cell 111 to be disposed on the edgeportion 9 a. By forming such opening portion J, a display region A islocated within the opening portion J, and the edge portion 9 a of thecasing 9 encloses the display region A, in a plan view.

Herein, the casing 9 is made of an electrically conductive material,such as a steel plate. Therefore, it becomes possible to inhibit a noisefrom entering an electronic component such as the liquid crystal panel11 due to an influence of an electromagnetic wave generated from thefluorescent discharge tube 2 or the like. Thus, the casing 9 can have ashield effect. A through-hole G which communicates with outside isprovided on the side portion 9 b of the casing 9, for a weight savingand an installation by a user. In the structure in which the lightingelement 20 is held by the casing 9, a space (specifically, a clearanceF) is formed between the light correction sheet 4 or the light guidingplate 1 and an inner wall of the side portion 9 b of the casing 9. So,it becomes possible to absorb a dimension difference by the clearance F,when the light correction sheet 4, the light guiding plate 1, and thecasing 9 expand with different expansion rates due to a temperaturevariation, thereby resulting in the dimension difference. As a result,it becomes possible to inhibit occurrence of distortion or the like.

Since the through-hole G is formed on the side portion 9 b of the casing9 as described above, dust enters the casing 9 from outside through thethrough-hole G. However, herein, the spacing H of the space between thelight guiding plate 1 and the light correction sheet 4 is not largerthan one pixel dimension, so that the dust larger than the spacing H ofthe dust which might enter the space through the clearance F, isinhibited from entering the space, and only the dust not larger than onepixel dimension (herein, not larger than 0.4 mm) enters the space. Adefect brought about by such small dust is, though it varies dependingon the liquid crystal cell 111 mounted, not larger than one pixeldimension, so that it does not have a large influence on a displayimage, unlike in a case where the defect arises over a plurality ofpixels. Therefore, it becomes possible to inhibit occurrence of inferiordisplay and a non-uniform luminance or the like. Also, by inhibitingentry of large dust in this manner, it becomes possible to inhibitdamage to components such as the light correction sheet or the like dueto a friction between the components and the dust.

The liquid crystal panel 11 comprising the display rear surface sidepolarizer 13 a, the liquid crystal cell 111, and the display frontsurface side polarizer 13 b, is provided on the lighting unit thusstructured, and a frame-shaped front cover 12 for holding thesecomponents is attached. Thus, the liquid crystal display device isformed. Herein, a transparent-type liquid crystal display devicecomprising a transparent-type liquid crystal panel 11 is described.

In this embodiment, unlike in a conventional structure (see FIG. 4) inwhich the display rear surface side polarizer 13 a is disposed on theedge portion 9 a of the casing 9, the display rear surface sidepolarizer 13 a is directly disposed on the front surface of the lightcorrection sheet 4 exposed in the opening portion J formed on the casing9. By thus disposing the polarizer 13 a directly on the light correctionsheet 4, a structure in which little space is formed between the lightcorrection sheet 4 and the polarizer 13 a can be realized. Since theopening portion J is smaller than the liquid crystal cell 111, a portionof the liquid crystal cell 111 disposed on the polarizer 13 a, whichoverlaps with the edge portion 9 a of the casing 9, is bonded to theedge portion 9 a by an adhesive tape 14 such as a double face adhesivetape. The space is formed between the light emanating surface of thelight guiding plate 1 and a lower surface of the light correction sheet4. Although this space is shown exaggeratedly in the drawings, thespacing H of the space is as small as not larger than one pixeldimension as described above, so that the space hardly affectsdeflection of the liquid crystal cell 111.

In the structure in which the little space is formed between the lightcorrection sheet 4 and the display rear surface side polarizer 13 a, theliquid crystal cell 111 is supported by a front surface of the flatdisplay rear surface side polarizer 13 a, if the display device ispushed from the display surface side of the liquid crystal cell 111. Tobe precise, the display rear surface side polarizer 13 a is supported bythe light correction sheet 4, and the light correction sheet 4 receivesa pressure from the liquid crystal cell 111 side through the displayrear surface side polarizer 13 a and is supported by the light emanatingsurface of the light guiding plate 1 such that it deflects as much asthe spacing H between the light emanating surface of the light guidingplate 1 and itself. Since the spacing H is very small as describedabove, deflection amount of the light correction sheet 4 is negligiblysmall as compared to allowable deflection amount of the liquid crystalcell 111. Therefore, the display rear surface side polarizer 13 a issubstantially supported by the light emanating surface of the lightguiding plate 1. In the above structure, since the liquid crystal cell111 and the like do not deflect substantially, it becomes possible toinhibit break of the liquid crystal cell 111 comprising glass substratesor the like. Especially, when a thickness of the edge portion 9 a of thecasing 9 is set substantially equal to that of the display rear surfaceside polarizer 13 a, an upper surface of the edge portion 9 a and anupper surface of the display rear surface side polarizer 13 a aresubstantially coplanar with each other. So, when a user accidentallypushes the liquid crystal cell 111 from the display surface sidethereof, the liquid crystal cell 111 uniformly contacts these flatsurfaces, and the entire cell 111 is uniformly supported. Therefore,deflection of the liquid crystal cell 111 and break of the same areinhibited. In addition, when the casing 9 is made of the steel plate asdescribed above, the edge portion 9 a can be formed to be equal inthickness to the thin display rear surface side polarizer 13 a, and itbecomes possible for the casing 9 to perform a function of holding thelighting element 20 by maintaining a strength or the like thereofregardless of the thin edge portion 9 a. And, it becomes possible toinhibit a noise from entering the electronic component of the liquidcrystal display device due to the influence of the electromagnetic wavegenerated from the fluorescent discharge tube 2 or the like.

As described above, in the lighting unit and the liquid crystal displaydevice comprising the same in this embodiment, it is possible to inhibitthe break of the liquid crystal cell due to the pressure from the panelside, and to inhibit the entry of the dust having influence on adisplay. So, it is possible to obtain a liquid crystal display devicethat can be used in products of various uses, including portable deviceused in severe surroundings such as outside. Such a liquid crystaldisplay is highly reliable and stable, and provides a satisfactorydisplay.

FIG. 3 is a cross-sectional view schematically showing a structure ofthe lighting unit and the liquid crystal display device comprising thesame according to another embodiment of the present invention.

As shown in FIG. 3, the lighting unit of this embodiment is identical instructure to the lighting unit of the above-described embodiment exceptthe following point. Specifically, in this embodiment, the edge portion9 a of the casing 9 is not formed on the light emanating surface side,so that the display region A is not enclosed by the casing 9 and isentirely opened. In this embodiment thus structured, as in theabove-described embodiment, since the display rear surface sidepolarizer 13 a is disposed directly on the light correction sheet 4, thesame effect as described above can be obtained. In the structure inwhich the edge portion 9 a of the casing 9 encloses the display regionA, as in the above-described embodiment, since the liquid crystal cell111 is disposed on the edge portion 9 a, positioning of the liquidcrystal cell 111 becomes easier, and the liquid crystal cell 111 can bebonded to and fixed to the casing 9. And, with only the lighting unitprovided, since the edge portion 9 a of the casing 9 holds the lightingelement 20 on the light emanating surface side, it is possible toadvantageously inhibit the lighting element 20 contained in the casing 9from getting detached.

While the L-shaped fluorescent discharge tube 2 is used in theabove-described embodiment, a U-shaped fluorescent discharge tube 2 maybe used in place of the L-shaped one, a light source other than thefluorescent discharge tube may be used, too. Furthermore, while thelighting unit of the edge light type is described in this embodiment,the present invention is applicable to the lighting unit of other types.

In addition, the transparent-type liquid crystal cell 111 is describedin this embodiment, the same effect will be obtained when the presentinvention is applied to a semitransparent-type liquid crystal displaydevice comprising a semitransparent-type liquid crystal cell 111.

Numerous modifications and alternative embodiments of the presentinvention will be apparent to those skilled in the art in view of theforegoing description. Accordingly, the description is to be construedas illustrative only, and is provided for the purpose of teaching thoseskilled in the art the best mode of carrying out the invention. Thedetails of the structure and/or function may be varied substantiallywithout departing from the sprit of the invention.

INDUSTRIAL APPLICABILITY

A lighting unit according to the present invention is useful as alighting unit in a liquid crystal display device used in a portablephone, a personal computer and the like. And, the liquid crystal displaydevice according to the present invention comprising the lighting unitis useful as a display device of the portable phone, the personalcomputer, or the like, especially as the display device which isrequired to be thin and light.

1. A liquid crystal display device comprising: a lighting unit including: a light source; a light guiding component for guiding light emitted from the light source and emanating the light from a light emanating surface to an object to be illuminated; a reflecting component covering at least a bottom surface of the light guiding component; a light correction component disposed on the light emanating surface of the light guiding component; and a casing for holding the light source, the light guiding component covered with the reflecting component, and the light correction component, wherein the casing has an opening portion in a region corresponding to a light emanating region of the light correction component, the object to be illuminated is disposed in direct contact with an upper surface of the light correction component within the opening portion, and a space is formed between the light guiding component and the light correction component, and a liquid crystal panel as an object to be illuminated disposed on a light emanating surface side of the lighting unit, the liquid crystal panel having a liquid crystal cell comprising a pair of transparent substrates with a liquid crystal layer interposed therebetween, wherein the liquid crystal panel is disposed in direct contact with a front surface of the light correction component within the opening portion of the casing of the lighting unit; the liquid crystal panel comprises a pair of polarizers with the liquid crystal cell interposed therebetween; a polarizer on the lighting unit side of the pair of polarizers has an outer diameter smaller than an outer diameter of the opening portion of the casing, and directly contacts a front surface of the light correction component within the opening portion; the casing has a frame-shaped edge portion protruding toward the opening portion so as to enclose the opening portion; and the liquid crystal cell is disposed on an upper surface of the edge portion.
 2. The liquid crystal display device according to claim 1, wherein a thickness of the edge portion of the casing is substantially equal to a thickness of the polarizer on the lighting unit side.
 3. The liquid crystal display device according to claim 1, wherein the casing is made of an electrically conductive material.
 4. The liquid crystal display device according to claim 1, wherein a spacing of said space formed between the light guiding component and the light correction component in the lighting unit is not larger than a dimension of each of pixels composing the liquid crystal cell.
 5. The liquid crystal display device according to claim 4, wherein the spacing of the space is 0.4 mm or smaller.
 6. The liquid crystal display device according to claim 4, wherein the casing has a through-hole to allow an outside of the casing and an inside of the casing to communicate with each other.
 7. The liquid crystal display device according to claim 1, wherein the light guiding component is a light guiding plate; the light source is disposed along a first end face of the light guiding plate; the reflecting component is a reflecting sheet; a bottom surface of the light guiding plate, the first end face of the light guiding plate and the light source, and a second end face of the light guiding plate on which the light source is not disposed are covered with the reflecting sheet; the light correction component comprises one or a plurality of light correction sheets; and the casing is frame-shaped and supports at least the bottom surface of the light guiding plate, the second end face of the light guiding plate, and the first end face of the light guiding plate and the light source, each of which is covered with the reflecting sheet.
 8. A liquid crystal display device comprising: a lighting unit comprising: a light source; a light guiding component for guiding light emitted from the light source and emanating the light from a light emanating surface to an object to be illuminated; a reflecting component covering at least a bottom surface of the light guiding component; a light correction component disposed on the light emanating surface of the light guiding component; and a casing for holding the light source, the light guiding component covered with the reflecting component, and the light correction component, wherein the casing has an opening portion in a region corresponding to a light emanating region of the light correction component, and the object to be illuminated is disposed in direct contact with an upper surface of the light correction component within the opening portion; and a liquid crystal panel as an object to be illuminated disposed on a light emanating surface side of the lighting unit, the liquid crystal panel having a liquid crystal cell comprising a pair of transparent substrates with a liquid crystal layer interposed therebetween, wherein the liquid crystal panel is disposed in direct contact with a front surface of the light correction component within the opening portion of the casing of the lighting unit, the liquid crystal panel comprises a pair of polarizers with the liquid crystal cell interposed therebetween, a polarizer on the lighting unit side of the pair of polarizers has an outer diameter smaller than an outer diameter of the opening portion of the casing, and directly contacts a front surface of the light correction component within the opening portion, the casing has a frame-shaped edge portion protruding toward the opening portion so as to enclose the opening portion, the liquid crystal cell is disposed on an upper surface of the edge portion, and a thickness of the edge portion of the casing is substantially equal to a thickness of the polarizer on the lighting unit side.
 9. A liquid crystal display device comprising: a lighting unit comprising: a light source; a light guiding component for guiding light emitted from the light source and emanating the light from a light emanating surface to an object to be illuminated; a reflecting component covering at least a bottom surface of the light guiding component; a light correction component disposed on the light emanating surface of the light guiding component; and a casing for holding the light source, the light guiding component covered with the reflecting component, and the light correction component, wherein the casing has an opening portion in a region corresponding to a light emanating region of the light correction component, and the object to be illuminated is disposed in direct contact with an upper surface of the light correction component within the opening portion; and a liquid crystal panel as an object to be illuminated disposed on a light emanating surface side of the lighting unit, the liquid crystal panel having a liquid crystal cell comprising a pair of transparent substrates with a liquid crystal layer interposed therebetween, wherein the liquid crystal panel is disposed in direct contact with a front surface of the light correction component within the opening portion of the casing of the lighting unit, and the casing is made of an electrically conductive material.
 10. A liquid crystal display device comprising: a lighting unit comprising: a light source; a light guiding component for guiding light emitted from the light source and emanating the light from a light emanating surface to an object to be illuminated; a reflecting component covering at least a bottom surface of the light guiding component; a light correction component disposed on the light emanating surface of the light guiding component; and a casing for holding the light source, the light guiding component covered with the reflecting component, and the light correction component, wherein the casing has an opening portion in a region corresponding to a light emanating region of the light correction component, and the object to be illuminated is disposed in direct contact with an upper surface of the light correction component within the opening portion; and a liquid crystal panel as an object to be illuminated disposed on a light emanating surface side of the lighting unit, the liquid crystal panel having a liquid crystal cell comprising a pair of transparent substrates with a liquid crystal layer interposed therebetween, wherein the liquid crystal panel is disposed in direct contact with a front surface of the light correction component within the opening portion of the casing of the lighting unit, and a spacing of a space formed between the light guiding component and the light correction component in the lighting unit is not larger than a dimension of each of pixels composing the liquid crystal cell.
 11. The liquid crystal display device according to claim 10, wherein the spacing of the space is 0.4 mm or smaller.
 12. The liquid crystal display device according to claim 10, wherein the casing has a through-hole to allow an outside of the casing and an inside of the casing to communicate with each other.
 13. A liquid crystal display device comprising: a lighting unit comprising: a light source; a light guiding component for guiding light emitted from the light source and emanating the light from a light emanating surface to an object to be illuminated; a reflecting component covering at least a bottom surface of the light guiding component; a light correction component disposed on the light emanating surface of the light guiding component; and a casing for holding the light source, the light guiding component covered with the reflecting component, and the light correction component, wherein the casing has an opening portion in a region corresponding to a light emanating region of the light correction component, and the object to be illuminated is disposed in direct contact with an upper surface of the light correction component within the opening portion; and a liquid crystal panel as an object to be illuminated disposed on a light emanating surface side of the lighting unit, the liquid crystal panel having a liquid crystal cell comprising a pair of transparent substrates with a liquid crystal layer interposed therebetween, wherein the liquid crystal panel is disposed in direct contact with a front surface of the light correction component within the opening portion of the casing of the lighting unit, and the light guiding component is a light guiding plate; the light source is disposed along a first end face of the light guiding plate; the reflecting component is a reflecting sheet; a bottom surface of the light guiding plate, the first end face of the light guiding plate and the light source, and a second end face of the light guiding plate on which the light source is not disposed are covered with the reflecting sheet; the light correction component comprises one or a plurality of light correction sheets; and the casing is frame-shaped and supports at least the bottom surface of the light guiding plate, the second end face of the light guiding plate, and the first end face of the light guiding plate and the light source, each of which is covered with the reflecting sheet. 